A man who says he was assaulted by a Labour Party staffer would like to meet with Jacinda Ardern to discuss the party's handling of claims of sexual abuse and assault.

The Prime Minister has refused to express full confidence in Labour president Nigel Haworth, who is under increasing pressure over the claims.

A 19-year-old volunteer claims she was sexually assaulted by the Labour staffer last year, and she raised it with Labour's ruling council during an internal investigation, but no disciplinary action was taken.

Another complainant has now spoken out, telling Checkpoint it was clear that the party "had no idea what they were doing" and that its internal investigation process was retraumatising for the victims.

Lisa Owen asks the complainant, whose voice we have distorted to protect his identity, to share his experience.

Checkpoint has seen a copy of an email sent from the complainant addressed to Labour Party President, Nigel Haworth, expressing dissatisfaction at the investigation.

The email was sent on May 21, 2019 and it explicitly includes the words "predatory behaviour, sexual violence, and physical violence".

Nigel Haworth declined to speak to Checkpoint, referring us to a three sentence statement he released earlier today.

The statement says the allegation of a sexual assault was not provided to the President and Acting General Secretary at a meeting in the Wellington Central Library or subsequently to the Labour Panel.

Checkpoint also sought comment from Andre Anderson and Dianna Lacy - we have not received a response as of Tuesday afternoon.